he Hubble Space Telescope site estimates there are hundreds of billions of galaxies in the universe. A recent German super-computer simulation estimates that the number may be as high as 500 billion, with many older than the Milky Way. Common obervational wisdom among astronomers is that there are 17 billion Earth-sized planets in our galaxy. They don't yet know how many of these worlds are in habitable zones, but the implications of this discovery are astounding. Simply put: If there are 17 billion Earth-sized worlds in our galaxy alone, it's clear that the Universe has the potential to be teeming with life.

A team of scientists lead by Francois Fressin of the Harvard-Smithsonian Center for Astrophysics, used the latest data from NASA's Kepler mission to find that one in six stars have "a planet 0.8 - 1.25 times the size of Earth in an orbit of 85 days or less." Extrapolated out to the Universe as a whole, the potential number becomes mind-boggling.

With the advent of powerful space infrared telescopes like the Spitzer Space Telescope and the (recently deceased) Herschel Space Telescope, astronomers have been able to study the properties of dust in galaxies so remote that their light has been traveling towards us for over ninety percent of the age of the universe. That these distant objects are detected at all is because they are very bright in the infrared, and they are bright because they are making huge numbers of stars whose light warms the dust that in turn radiates at infrared wavelengths.

In the image below A field of distant galaxies as seen at long infrared wavelengths over a region about one-third the size of the moon. The poor spatial resolution of infrared telescopes coupled with the great distances of the galaxies preclude seeing their spiral (or other) structures, but their different colors are apparent. A new study of 2500 distant infrared galaxies concludes they are more varied than local galaxies, probably due to different kinds of dust and dusty conditions in these early objects.

Local galaxies - those only hundreds of millions of light-years away in our cosmic neighborhood - provide a template for understanding how galaxies behave, and are the basis for models of their distant cousins. It has been known for decades that the early universe was actively making stars in galaxies. A key question for astronomers is whether distant galaxies are different enough from local ones that different physical processes need to be included in the models, or whether comparisons with local objects are valid.

CfA astronomer Ho Seong Hwang and a large team of his collaborators have analyzed a large sample of distant galaxies to address this question. The Herschel Space Telescope during its lifetime observed many distant infrared galaxies. The astronomers selected 2500 of them from a set of over fifty thousand, based on their having clear detections at several infrared wavelengths with ancillary data from other missions. The sample was selected in a way that was independent of observer preferences, like extreme brightness, that might compromise the conclusions, the first time this has been done for such a large sample.

The results were surprising. The scientists found that the dust in remote luminous galaxies tended to be warmer than it is in local galaxies of the same luminosity. Together with other indicators, the data suggest that the character of the dust and its environments have evolved with time in ways that are still not well known. Probably as a result of the dust variations there also appears to be a greater diversity of types of galaxies in the early universe.

Finally, the new paper notes, in accord with other recent papers, that there are indications that these galaxies may have started forming sooner after the big bang than had been anticipated in some old models.

In 2012, the Brightest of Reionizing Galaxies (BoRG) survey, which uses Hubble's WFC3 to search for the brightest galaxies around 13 billion years ago, when light from the first stars burned off a fog of cold hydrogen in a process called reionisation located five clustered galaxies so distant that their light has taken 13.1 billion years to reach us. We are seeing them just 600 million years after the Universe's birth in the Big Bang.

Galaxy clusters are the largest structures in the Universe, comprising hundreds to thousands of galaxies bound together by gravity. This developing cluster, or protocluster, seen as it looked 13 billion years ago, presumably has grown into one of today's massive cities of galaxies, comparable to the nearby Virgo cluster of more than 2000 galaxies.

"These galaxies formed during the earliest stages of galaxy assembly, when galaxies had just started to cluster together," says the study's leader, Michele Trenti (University of Cambridge, UK and University of Colorado). "The result confirms our theoretical understanding of the buildup of galaxy clusters. And, Hubble is just powerful enough to find the first examples of them at this distance."

Most galaxies in the Universe reside in groups and clusters, and astronomers have probed many of these in detail at a range of distances. But finding clusters in the early phases of construction has been challenging because they are rare and dim.

"We need to look in many different areas because the odds of finding something this rare are very small," says Trenti who used Hubble's sharp-eyed Wide Field Camera 3 (WFC3) to pinpoint the galaxy clusters. "It's like playing a game of Battleship: the search is hit and miss. Typically, a region has nothing, but if we hit the right spot, we can find multiple galaxies."

Because these distant, fledgling clusters are so dim, the team hunted for the systems' brightest galaxies. These brilliant galaxies act as billboards, advertising cluster construction zones. From simulations, the astronomers expect galaxies at early epochs to be clustered together. Because brightness correlates with mass, the most luminous galaxies pinpoint the location of developing clusters.

These powerful light beacons are found in deep wells of dark matter, an invisible form of matter that makes up the underlying gravitational scaffolding for galaxy formation. The team expects many fainter galaxies that were not seen in these observations to inhabit the same neighborhood.

The five bright galaxies spotted by Hubble are about one-half to one-tenth the size of our Milky Way, yet are comparable in brightness. The galaxies are bright and massive because they are being fed large amounts of gas through mergers with other galaxies. The team's simulations show that the galaxies will eventually merge and form the brightest central galaxy in the cluster, a giant elliptical radio similar to the Virgo Cluster's Messier 87 (image at top of page).

These observations demonstrate the progressive buildup of galaxies and provide further support for the hierarchical model of galaxy assembly, in which small objects accrete mass, or merge, to form bigger objects over a smooth and steady, but dramatic, process of collision and collection.

The team estimated the distance to the newly found galaxies based on their colors. Astronomers now plan to follow up with spectroscopic observations, which will help them precisely calculate the cluster's distance. These observations will also yield the velocities of the galaxies and show whether they are gravitationally bound to each other.

The image below at left, taken in visible and near-infrared light, reveals the location of five galaxies clustered together just 600 million years after the Universe’s birth in the Big Bang. The circles pinpoint the galaxies. The sharp-eyed Wide Field Camera 3 aboard the NASA/ESA Hubble Space Telescope spied the galaxies in a random sky survey.

The developing cluster is the most distant ever observed. The average distance between them is comparable to that of the galaxies in the Local Group, consisting of two large spiral galaxies, the Milky Way and the Andromeda Galaxy, and a few dozen small dwarf galaxies. The close-up images at right, taken in near-infrared light, show the galaxies.

Simulations show that the galaxies will eventually merge and form the brightest central galaxy in the cluster, a giant elliptical similar to the Virgo cluster’s Messier 87. Galaxy clusters are the largest structures in the Universe, comprising hundreds to thousands of galaxies bound together by gravity. The developing cluster presumably will grow into a massive galactic city, similar in size to the nearby Virgo Cluster, a collection of more than 2000 galaxies.

you scientists need to wake up! you guys know that there are unlimited galaxies out there you just want to put a estimate on the universe because you know that we will never get the tech to discover every galaxy.

The universe filled with life? The whole game of the probability of other life in the universe being based on the number of possible planets out there is ridiculous. Here we are on a planet full of life from order. It is not violent and chaotic events this comes from. God is and always was. Give the Lord some credit will ya!

As I said before in nov.2012 on this site, do you think the universe exist just for us planet earth? There are billions of planets in the universe like our earth.I don't believe in BIG BANG THEORY.Our universe always existed, no beginning no end, it's GOD maybe as we know. We are going to other planets once we died here. That's my theory. The quality of life after death will depend for what we accomplished here. Religions created wars since our planet existed and we still at war in 2014. That's my hummble opinion which you don't have to agree people.

This is not my area of expertise, I am just an avid student of space. I apologize in advance if what I'm about to ask sounds stupid. The following are quotes from the 1st paragraph "Common obervational wisdom among astronomers is that there are 17 billion Earth-sized planets in our galaxy...." "Simply put: If there are 17 billion Earth-sized worlds in our galaxy alone, it's clear that the Universe has the potential to be teeming with life." I have never ever even once heard a claim that there are 17 Billion earth size planets in our galaxy, let alone twice in the same paragraph. What the hell are you talking about? Or does someone need to start proofing this web site? I have literally spoke with hundreds of astronomers and not one has ever said that. I'm thinking you meant to say, "in our observable universe...." Right?

I saw a u-tube of Stephen Hawking saying he doesn't believe in God and once we die it's over! I find it's strange for a man who studied the universe all his life, making theories, teaching, conferences all over the world to make such judgment. It's a real paradox, nobody hnow what will happen after death. For myself I prefer to believe something wonderful will occur when we die.

Trying to measure the size of the universe is like trying to measure the age of God who created all things. We understand that God has always been there and is everlasting so how can you measure the size and age of a universe that was created by one who has always existed. All this is merely guess work done by our finite minds. If you believed the scriptures you would know that there are innumerable worlds that have life out there and trying to determine how many galaxies are there in the universe from this fallen world is an impossible thing.

Trying to measure the size of the universe is like trying to measure the age of God who created all things. We understand that God has always been there and is everlasting so how can you measure the size and age of a universe that was created by one who has always existed. All this is merely guess work done by our finite minds. If you believed the scriptures you would know that there are innumerable worlds that have life out there and trying to determine how many galaxies are there in the universe from this fallen world is an impossible thing.

I predict that the scientists will NEVER FIND REAL BIOLOGICAL LIFE AS WE HAVE even In a thousand years. We were created here for a purpose - and we are the purpose of the entire universe.
let every person search to understand that purpose. I have searched and found to my satisfaction what it is.

Sounds like kind of a waste doesn't it? Creating billions upon billions of galaxies, each filled with billions and billions of stars, to give purpose to one species on one ball of rock orbiting one average-sized star?

Oh, there's life out there all right, and intelligent life too. But we're not gonna ever reach it, nor it us. If worm holes do exist, then that might be a way, but how to harness such a phenomenon to propel us to solar systems containing such life, and then get us back again??..that's the question. Maybe it's not space we should be looking longingly at, but other dimensions. If time and space are relative fabrics and can bend, then surely we can find a way through them, and discover new life and new worlds that way. I also believe that although intelligent alien life from light years away has never visited our world, life forms from different dimensions may have done so, and even humans from our own future. It is feasible that mankind will one day discover and harness time travel, and make trips back to the past. Hence the close encounters we've read about may be more to do with future and present humans hooking up, rather than alien encounters.

The heavens declare the glory of God; the skies (firmament) proclaim the work of his hands. Psalms 19:1

Lift up your eyes and look to the heavens: Who created all these? He who brings out the starry host one by one and calls forth each of them by name. Because of his great power and mighty strength, not one of them is missing. Isaiah 40:26

This is what God the Lord says—
the Creator of the heavens, who stretches them out,
who spreads out the earth with all that springs from it,
who gives breath to its people,
and life to those who walk on it: Isaiah 42:5

What has religion got to do with Scientific facts? Next you will be telling me that Penguins and Polar Bears walked from the Arctic to get on a Giant Lifeboat and that the world flodded and killed everyone except one family. Religion is just a story for folks that are scared of dying.

To me it is simply a question of logic. A Bishop named Usher, about 1870, figured the chronological history of the bible backwards and concluded that God created the world in 4004 BC. A Pope then recalculated and figured it was about 5,000 BC. The Bible is a chronological history. If that is so then there couldn't have been dinosaurs roaming the earth 75 million years ago. The evidence for evolution is overwhelming and beyond dispute, so it is evident that what is in the Bible are fables and fairy stories concocted by
superstitious people. PERIOD

As per the ancient vedic science of india the universe is a never ending cycle. Every thing is created or formed, goes through three stages. Creation or formation , existance, and distruction. That is applicable to the whole universe. If we start from here , the sun is burning for millions of years and keep burning for many more years. As it keep burning and loosing its energy the gravity cannot hold it together and it will start expanding , consuming everything in the solar system, first by liquidfying then vaporising. Everythin got its boundary and when reach the boundary, it is like touching north pole of a magnet touching another north pole and the whole thing is thrown back to the centre and become what the modern science call the black hole. Every stars in the galaxies die when time comes. After the big bang every thing is thown out with a tremendous force and it keep trveling. Actualy it is not going away from the center. Every thing travel in circle. If we sent a missail streight up in the sky ., it will fall back at the same spot once the power is over. Suppose it take 6 hours to come back , the earth would have taken a quarter turn by then. Still it will fall at the same spot . Every thing in nature has the tendency to come back to where it came from. So once the time is up all stars will burn up, become a black whole and keep its travel till it reach back to where it came from and that is the end of a cycle. At that time total sum of the universal energy is concentrated at one spot and remain there as a potential energy. As the pressure grow up it will explode again. So according to veda every thing came from one single energy and eveything we see around is a part of the same universal energy called god.